According to the statement, the attack was carried out by several foreign-backed militant groups, including the al-Qaeda-linked Ahrar al-Sham.

Kurdish sources said several people were rushed to a hospital following the chemical attack. The victims were reportedly suffering from the common symptoms of chemical poisoning.

Despite an agreement on the cessation of hostilities in Syria, which was negotiated by the US and Russia and which went into force on February 27, fighting has continued in Aleppo Province during the past days.

The YPG had previously reported that the militants operating in the area had not been respecting the agreement and were continuing to attack Kurdish areas.

On Monday, some nine people, including a family of seven, were killed in a shelling in the city of Aleppo. Another 16 people lost their lives after militants fired dozens of rockets on Sheikh Maqsoud a day earlier.

The YPG also says that Turkey has recently fired artillery shells at Kurdish fighters in northern Syria, effectively violating the agreement.

There is a hodgepodge of factions fighting in Syria. A number of regional countries have been backing various armed groups. Turkey, though, has been the only regional country directly firing into Syria, hitting what it says are Kurdish targets, who are themselves fighting extremist groups inside Syria including Daesh terrorists.

Syria has been gripped by foreign-backed militancy since March 2011. According to a February report by the Syrian Center for Policy Research, the five-year-long conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced nearly half of the country’s pre-war population of about 23 million within or beyond its borders.